HOT FORMING STEEL PIPE HAVING MULTI-MICROSTRUCTURE DUE TO DIFFERENT COOLING AND METHOD OF MANUFACTURING THE SAME

摘要

The present invention provides a manufacturing method of a hot forming steel pipe, which secures stiffness and absorbs impact at the same time. The manufacturing method of the hot forming steel pipe according to an embodiment of the present invention comprises: a step for heating a steel pipe composed of 0.32-0.38 wt% of carbon; a step for inserting the steel pipe inside a mold which has a slow cooling region and a rapid cooling region therein and to which cooling fluid is sprayed in the rapid cooling region; and a step for hot-forming the steel pipe by pressing the mold toward the steel pipe and differentially cooling the steel pipe by using the cooling fluid.